Load detecting device for generator

Abstract

A load detecting device for a generator driven by an engine and supplying power to a load includes a rotary angle detector for producing a pulse signal at every predetermined rotary angle of the generator or engine, a load detector for detecting a load current of the generator, and an output unit for receiving the outputs from the rotary angle detector and load detector, and outputting a load signal of the generator. The load detector produces a voltage signal corresponding to a detected load current. The load signal output unit takes out a voltage value of the voltage signal from the load detector at every rotary angle capable of detecting a load change on the base of the pulse signal from the rotary angle detector, and outputs said voltage value as the load signal.

What is claimed is: 
     
       1. A load detecting device in a control system for an engine driving a rotary A.C. generator to supply A.C. current to a load which may fluctuate, comprising: load current detector means for detecting the A.C. current supplied by said A.C. generator to said load and for developing an A.C. current value signal indicative thereof;   rotary angle detector means for developing a pulse train signal including a pulse for each predetermined incremental angle of rotation of said A C. generator; and   load signal output means, responsive to said A.C. current value signal and said pulse train signal, for developing an output signal representative of the value of said A.C. current value signal at the time a said pulse of said pulse train signal is received, said output signal being updated to a new value of said A.C. current value signal upon receipt of each said pulse of said pulse train signal.   
     
     
       2. The device of claim 1 further comprising means for controlling said engine in response to said output signal. 
     
     
       3. The device of claim 1, wherein said load current detector means comprises a current transformer for detecting said load current, and a resistor inserted in parallel with an output side of said current transformer for providing said A.C. current value signal. 
     
     
       4. The device of claim 3, wherein said rotary angle detector means comprises a pulser and pickup which generate an induction voltage at or near the maximum amplitude of said A.C. current value signal at every one cycle thereof, and a waveform shaping circuit which receives said induction voltage and develops said pulse train signal. 
     
     
       5. The device of claim 3, wherein said rotary angle detector means comprises: a pulser and pickup which generate a plurality of induction voltages at predetermined angle intervals during one cycle of said voltage signal,   a waveform shaping circuit, responsive to said induction voltages, for developing a pulse train, and   a divider, responsive to said pulse train, for developing each pulse of said pulse train signal at or near a phase angle of the maximum amplitude of said A.C. current value signal at every one cycle of said voltage signal.   
     
     
       6. The device of claim 1, wherein said load current detector means comprises: a current transformer for detecting said load current,   a resistor inserted in parallel with an output side of said current transformer and providing an A.C. voltage representative of said load current, and a full-wave rectifier circuit which receives said A.C. voltage from said resistor and provides a full-wave rectified signal as said A.C. current value signal;   wherein said rotary angle detector means provides a pulse of said pulse train signal at or near a phase angle of a maximum amplitude of said A.C. current value signal at every half cycle thereof.   
     
     
       7. The device of claim 5, wherein said rotary angle detector means comprises a pulser and pickup which generate an induction voltage at or near maximum amplitude of said A.C. current value signal at every half cycle thereof, and a waveform shaping circuit which receives said induction voltages and develops said pulse train signal. 
     
     
       8. The device of claim 6, wherein said rotary angle detector means comprises: a pulser and pickup which generate a plurality of induction voltages at predetermined angle intervals during each cycle of said voltage signal,   a waveform shaping circuit, responsive to said induction voltages, for developing a pulse train, and   a divider, responsive to said pulse train, for developing each pulse of said pulse train signal at a phase angle at or near the maximum amplitude of said voltage signal at every half cycle thereof.   
     
     
       9. The device of claim 1, wherein said load signal output means is a sample-and-hold circuit which holds said A.C. current value signal received from said load signal detector means upon receipt of said pulse of said pulse train signal from said rotary angle detector means, to provide said output signal. 
     
     
       10. The device of claim 1, wherein said load signal output means includes an A/D converter for A/D converting said A.C. current value current from said load signal detector means, and a latch circuit for latching an output of said A/D converter in response to said pulse signal from said rotary angle detector means, to provide said output signal. 
     
     
       11. The device of claim 2, wherein said means for controlling controls the rotational output speed of said engine to be relatively constant. 
     
     
       12. The device of claim 2, wherein said means for controlling varies the supply of fuel to said engine. 
     
     
       13. The device of claim 12 wherein said engine is a diesel engine.